a) The derivative dy/dx of the equation is: dy/dx = -10x^{4}. If you don't remember this, revise Power Rule for derivatives.b) The equation of a line is given by y = mx + q. To find the tangent line at a point, we need: 1) Find the slope of the line by substituting that point in the equation of the derivative m = dy/dx (x=1) = -10. 2) Solve the system between the curve and the line at x=1 to find q. We find q=15. The equation of the line is therefore: y = -10x + 15